//
// Created by Senhai Xu on 2024/7/5.
//

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) : val(x), next(nullptr) {}
};

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param head ListNode类
     * @return ListNode类
     */
    ListNode* ReverseList(ListNode* head) {
        // write code here
        if(head == nullptr||head->next== nullptr) return head;
        ListNode* pre = head;
        ListNode* cur = head->next;
        ListNode* next = cur->next;
        head->next = nullptr;
        while(cur!= nullptr){
            cur->next = pre;
            pre = cur;
            cur = next;
            if(next!= nullptr) next = next->next;
        }
        return pre;
    }
};